The preparation of iodine (III)-phosphate reagents, PhI(OR)OP(O)(OR')2, and their efficacy for the synthesis of phosphate esters via the direct phosphoryloxylation of carbon (as opposed to the phosphorylation of oxygen) will be explored. Particular emphasis will be given to reagents with R' groups (e.g. -SiMe3, -CH2CH2CN) amenable to selective removal under mild conditions once the phosphate ligand is introduced into organic substrates. The synthesis of iodine (III) reagents with the dihydrogen phosphate ligand, (HO)2PO2-, will also be given high priority. The functionalization of ketones and beta-dicarbonyl compounds, silyl enol ethers, silyl ketene acetals, alkenes, conjugated dienes, alkynes and alkenoic acids with the iodine(III)-phosphates will provide a variety of new unnatural phosphate esters with considerable structural diversity. A major effort will be made to apply hypervalent iodine methodology to the synthesis of biologically important phosphate esters. An economical synthesis of dihydroxyacetone phosphate from propargyl alcohol is delineated, and a new approach to the pentofuranose-3- and 5-phosphates by the phosphoryloxylactonization of alkenoic acids is proposed. The generation of iodine(III) reagents from iodosobenzene and acyl phosphates and their reactions with long-chain esters of allyl alcohol will be explored as a synthetic entry into the phosphatidic acids. The preparation of iodine(III)-phosphates in which the phosphate ligand is provided by a ribonucleotide and the direct incorporation of the ribonucleotide into ketones (alpha-carbon), lactones etc. will also be investigated. The health-relatedness of this project is attested to by the ubiquity of phosphate esters in biological systems; it is hard to imagine life without them. Phosphate esters in biological systems; it is hard to imagine life without them. Phosphate esters, among other things, serve as structural components (DNA, RNA, cell membranes), metabolic and biosynthetic intermediates (carbohydrates, amino acids, steroids, terpenes) and coenzymes and play a crucial role in biological energy flow. The availability of iodine(III)-phosphates offers a new and versatile approach to a variety of known and unknown phosphate esters many of which would be difficult to prepare by the current methods of synthesis.